Confirmation of 137Cs dating by algal stratigraphy in Rostherne Mere
Confirmation of 137Cs dating by algal stratigraphy in Rostherne Mere
复制标题
通过 Rostherne Mere 的藻类地层学确认 137Cs 年代测定
作者：
D. Livingstone;R. S. Cambray
柴郡 Rostherne Mere 的深层沉积物（国家网格参考号 SJ 745843）为在没有总体生物扰动的情况下研究生物分层和放射性核素测年之间的关系提供了一个有希望的情况。该区域面积较小（46.5 公顷），但相对较深（最大 30 m），据报道，在持续脱氧的深层沉积物中基本上没有底栖动物群。除硅藻外，罗瑟恩湖的沉积物中还含有多种藻类的遗迹。尽管在苏联的腐泥沉积物中发现了非硅质藻类的保存，但其保存并不常见。在 Rostherne 中，Ceratium hirundinella O.F. 的空孢子。 Mull.、鱼腥藻属和 Aphanizomenon flos-aquae (L) Ralfs 都是可识别的，微囊藻属的菌落和 Staurastrum 属的细胞也是如此。自 1912 年以来，Rostherne Mere 的浮游植物一直被定期记录（参考文献 3-5），并从 1962 年开始更频繁地采样（参考文献 6-8）。最近的记录（表 1）显示夏季优势度的波动，主要是在 Ceratium hirundinella 和 Microcystis aeruginosa Kütz 之间。修正，但蓝绿藻已变得越来越占主导地位9。这些变化，加上硅藻 Melosira capsulata (Ehr.) Ralfs、Cyclotella pseudostelligera Hust 的偶尔出现极大化。和 Stephanodiscus astraea (Ehr.) Grun.，可以与沉积物中的藻类组合相关联，并可以准确地确定年代。我们现在报告说，湖沉积物中的此类藻类遗骸已被用来建立详细的年代学，该年代学证实了 137Cs 测年方法。
THE deep sediments of Rostherne Mere, Cheshire (National Grid Reference SJ 745843) offer a promising situation in which to study the relationship between biological stratification and radionuclide dating in the absence of gross bioturbation. The mere is small (46.5 hectare), but relatively deep (30 m maximum), and is reported to be largely devoid of benthic fauna in the persistently deoxygenated deep sediments1. The sediments of Rostherne Mere contain the remains of a great variety of algae, in addition to diatoms. The preservation of non-siliceous algae is uncommon, although found in the sapropel deposits of the USSR2. In Rostherne the empty spores of Ceratium hirundinella O.F. Mull., Anabaena species and Aphanizomenon flos-aquae (L) Ralfs are recognisable, as are colonies of Microcystis species and cells of Staurastrum species. The phytoplankton of Rostherne Mere has been recorded at intervals since 1912 (refs 3–5) and sampled more frequently from 1962 (refs 6–8). The recent records (Table 1) show fluctuations in summer dominance, mainly between Ceratium hirundinella and Microcystis aeruginosa Kütz. emend., but blue–green algae have become increasingly dominant9. These changes, combined with occasional maxima of the diatoms Melosira granulata (Ehr.) Ralfs, Cyclotella pseudostelligera Hust. and Stephanodiscus astraea (Ehr.) Grun., can be correlated with algal assemblages in the sediments and permit these to be accurately dated. We now report that such algal remains from the lake sediment have been used to establish a detailed chronology which is shown to confirm the 137Cs dating method.